1. Technical Field
The present invention relates to a door lock apparatus equipped with safety switch which operates, for example, to lock a protective door to industrial machines or such in a closed state.
2. Background Art
Conventionally, a safety switch is provided at a protective door or the like openably closing a doorway (opening) to a working area which is defined by partitioning walls and in which industrial machines such as machine tools or machining robots are installed. In order to prevent an operator from being involved in an accident in the working area, the safety switch is designed to de-energize the industrial machines when the protective door is open. As one example of such a safety switch, there is known a safety switch provided with a door lock apparatus with safety switch, as set forth in Patent Document 1. The locking apparatus is arranged such that the protective door is locked in the closed state unless a pivotal handle disposed at the protective door is manipulated to perform an operation of extracting an actuator from the safety switch, whereby the protective door is prevented from being opened.
This kind of door lock apparatus with safety switch operates as follows. In a case where the protective door is closed so that the industrial machines are in operation, the actuator fixed to the door is kept inserted in the safety switch installed at the doorway in the partitioning wall whereby the safety switch and the actuator are maintained in engagement such as to lock the protective door in the closed state. Thus, the protective door is prevented from being opened. In a case where the operator enters the working area, the operator may turn the pivotal handle for operatively opening/closing the door from a vertical position to a horizontal position, whereby the actuator, as interlocked with the pivotal handle so manipulated, is accommodated in a lock mechanism portion so as to be extracted from the safety switch. As a result, a stop signal is generated to disable the industrial machines, while the protective door is released from the state locked by the actuator and placed in an openable state.    Patent Document 1: Japanese Unexamined Patent Publication No. 2004-353849 ([0018], FIG. 1)